In semiconductor fabrication multiple die or circuits are fabricated on a single substrate. As part of the manufacturing process of integrated circuits the die are separated and individually packaged. Commonly, substrates are cut by means of a scribing tool that indents the device side. Die may also be separated by cutting took as well.
Also, the die may be separated in a production environment, or in a laboratory environment. In a laboratory environment the circuits are typically designed and tested, or may be tested as part of a production sampling and testing program. It is typically advantageous to separate the die for individual testing or packaging or to sub-sample the die to verify critical dimensions and metallurgy. In production, such separation may be achieved by utilizing complex high rate equipment that may utilize machine vision, precision alignment, vacuum hold downs, and the like to process a large number of cuts at a high rate. While accurate and fast, such equipment may not be practical due to its expense and complexity in a small production facility or laboratory environment where the design and testing of integrated circuits may be performed.
Typically, in such laboratory, or development and testing environments, scribing of a substrate may be done by scribing the top, along the length of the wafer to downsize the wafer for subsequent testing or analysis. A ruler or guide may be placed on top of the integrated circuit to guide the scribing of the top surface. Such practices can tend to damage the integrated circuit. If the top of the integrated circuit has not had a final stage glass passivation layer disposed on it, or other final processing, the wafer surface is particularly susceptible to damage. This is especially the case of wafers that are removed from the process stream for testing prior to the final stages of processing.
Such a guide may be placed with the aid of magnification to align the scribe and subsequent fracture between die. However, if the scribe line is still positioned via straight edge the circuit may be damaged. If it is attempted to scribe the back to avoid damaging die by the cleaving process, no amount of front side magnification will help align the scribe mark relative to the front side features to accurately cleave between the die, since the operator would essentially be working blind in placing the back surface scribe.
Accordingly, there is a need for a device that accurately scribes the back of the wafer with reference to top side features, to avoid damaging features on the top by ruler placement and scribing on the top. However as mentioned, if scribing is performed on the back of the work piece, it may be difficult to place the scribe line (and ultimately perform the cleaving) in reference to the circuit features on the top of the wafer so such features are not cut into, or otherwise damaged by an inaccurate separation if such a scribed line is made on the back of the wafer it is typically difficult to position such a scribe line so that features on the top of the wafer are not cut into.
Accordingly, it may also, be advantageous to provide a device that aids in positioning and scribing the back side of a wafer, while also providing structure aiding aligning such a back side scribing relative to features on the wafer top surface.
Further yet, there is a need for such a device and method to include enabling the operator to observe, by naked eye or by magnification (i.e. stereoscope) the device side while making the back sided scribe and subsequent cleaving of the substrate to further improve accuracy.
Thus, there is a need in the art an improved tool and method for scribing substrates (both crystalline and amorphous) without contacting the device side, while enabling the operator to reference the device side, and further to enable scribing the back side with scribe lines using references or a scale or both, relative to the device side—and to make such lines without powered cutting tools, and other unneeded and costly complexities.